11. Once environmental damage ______, it takes many years for the system to recover.
　　A. has done B. is to do C. does D. is done
　　12. Neither of the young men who had applied for a position in the university ______.
　　A. has been accepted B. have been accepted
　　C. was accepted  D. were accepted
　　13. The last half of the nineteenth century _____ the steady improvement in the means of travel.
　　A. has witnessed  B. was witnessed
　　C. witnessed  D. is witnessed
　　14. If she doesn’t tell him the truth now, he’ll simply keep on asking her until she _____.
　　A. does B. has done C. will do D. would do
　　15. My train arrives in New York at eight o’clock tonight. The plane I would like to take from there ______ by then.
　　A. would leave B. will have left C. has left D. had left
　　16. A thief who broke into a church was caught because traces of wax, found on his clothes, ______ from the sort of candles used only in churches.
　　A. had come B. coming C. come D. that came
　　17. She ought to stop work; she has a headache because she ______ too long.
　　A. has been reading  B. had read
　　C. is reading  D. read
　　18. This kind of glasses manufactured by experienced craftsmen ______ comfortably.
　　A. is worn B. wears C. wearing D. are worn
　　19. ―“May I speak to your manager Mr. Williams at five o’clock tonight?”
　　―“I’m sorry. Mr. Williams ______ to a conference long before then.”
　　A. has gone  B. had gone
　　C. would have gone  D. will have gone
　　20. By the time he arrives in Beijing, we ______ here for two days.
　　A. have stayed B. shall stay
　　C. have been staying D. will have stayed

　　21. Jack wishes that he ______ business instead of history when he was in university.
　　A. had studied B. study
　　C. had been studying D. studied
　　22. All the tasks ______ ahead of time, they decided to go on holiday for a week.
　　A. been fulfilled B. were fulfilled
　　C. having been fulfilled  D. had been fulfilled
　　23. By the time you get to New York, I ______ for London.
　　A. would be leaving   B. am leaving
　　C. have already left D. shall have left
　　24. Such crimes may be so complex that months or years go by before anyone ______ them.
　　A. discovered         B. will discover       C. would have discovered  D. discovers
　　25. By the end of next year, they ______ three modern hotels there.
　　A. will build B. will be building
　　C. will have been built D. will have built
　　26. Mr. Jones told me the other day that the Board of Directors _____ to put Peter in charge of the work.
　　A. decided            B. has decided
　　C. have decided           D. had decided
　　27. John' s score on the test is the highest in the group; he _____ last night.
　　A. should have studied     B. must have studied
　　C. has studied       D. should study
　　28. He's only got one shirt because all the rest _____ being washed.
　　A. is to be    B. is    C. will be    D. are
　　29. He _____ with Smith at least four times in the past three years.
　　A. has been seen to meet    B. was seen to meet
　　C. had been seen meeting    D. is seen meeting
　　30. They fulfilled the plan much earlier than they _____.
　　A. have expected    B. are expected
　　C. were expected    D. had expected